Air-conditioning apparatus with defrosting means



P 1949- c. L. RINGQUIST ETAL AIR CONDITIONING APPARATUS WITH DEF'ROSTINGMEANS Filed Aug. 21, 1946 2 Sheets-Sheet 1 bniom 526m JNVENTORSC.L.Rmsquls'r & ROBERT G.MINEP.

HTTORfiYS I Patented Sept. 5, 1949 UNITED STATES PATENT OFFICEAIR-CONDITIONING APPARATUS WITH DEFROSTING MEANS Clarence L. Ringqulstand Robert G. Miner, La

Crosse, La Crosse, Wis.

Win, assignors to The Trane Company,

Application August 2t, 1946, Serial No. 691,952

3 Cla,

apparatus. 5

It is well known that where air or gas must be dehumidified to acondition at or below the frost point, a duplication of equipment isrequired so that the air or gas can be delivered on a continustages forconditioning air or gas, whereby the air or gas may be economicallydehumifled and reheated in a comparatively small space.

Another object of this invention is to provide an apparatus which willcondition air or gas by dehumidiiying it and subsequently reheating itso that the conditioned air or gas will have a continuous uniformmoisture content and dry bulb temperature.

Still another object of the present invention is to provide a means ofcontrol whereby the conditioned air or gas will be uniform as tomoisture content and dry bulb temperature.

With the foregoing and other advantages in view, this invention consistsin the apparatus and system hereinafter described and claimed andfiustrated 1n the accompanying drawings where- Fig. 1 is a diagrammaticview of a. preferred and practical embodiment of the new and improvedair or as conditioning system, and

Fig. 2 is a simplified diagrammatic view of the cycles of operation ofthe new and improved air or gas conditioning system.

ous basis without shutting down the equipment It is to be understoodthat these drawings are for removal of ice or frost accumulations. Theillustrative of the present invention, and are not present inventionpets a considerable saving to be considered as limitations thereof,since variin refrigeration since the total amount of refrlgous changesand modifications may be made witheration is available for the purposeof conditionout departing from the spirit of the invention or ing thisair or gas, and at the same time the nethe scope of the appended claims.cessity oi duplicating certain of the equipment Referring to thedrawings in which th am is eliminated. reference numerals have been usedto indicate One object of the present invention, then, is to the Same,like P d fi st ad t n t i provide an apparatus for conditioning air orgas, Fig. 1, the reference numeral it indicates genparticularly when theair or gas must be coner -11y an inlet duct or pipe through which air orditionecl to a temperature at or below the frost s i moved by he fan ithrough either the duct point, it or it, then through the duct space 20,and Another object of this invention is to provide then through eitherduct it or it to the outlet an apparatus which will allow air or gasthat has duct 22. The system may be arranged in either been conditionedbelow the frost point to be de- 5 horizontal or vertical position asdesired. livered on a continuous basis without the neces- As a typicalillustration to aid in the undersity of using more than one system orapparatus standing of the operation of this new and novel for thispurpose. apparatus, assume the following conditions:

Still another object of the present invention is Gas at 70 F. saturatedis to b condit d to provide an apparatus which will deliver on a 30 toF. saturated when leaving coil as in duct continuous basis, in onedirection, air or gas that it or when leaving coil 26 in duct it. This70 has been conditioned below the frost point withg s enters thepparatus through the inlet duct out the necessity of shutting down theapparatus it into the duct l6the duct it being closed by for defrosting.the damper 24- The gas then passes over the Another object of thepresent invention is to 35 c il 6. def osting that coil, provided aprevious provide an apparatus for conditioning air or gas cycle hasoccurred. The gas then passes out of which may use warm, unconditionedair or gas h t and into he duct pace ZIP-the to defrost the coolingcoils in this apparatus. amp r 2 ei 11 an open position. The Yet anotherobject or the present invention is damper 30 meanwhile is in closedposition, thus to provide a sequence of cooling and reheating 4Q forcinh as o pass over the coil 32 where it is reduced to 57.5 F. saturated.The gas then flows into the duct l6the damper 34 being in open position.The gas then passes over coil 36 and is reduced to 25 F. saturated. Thegas then leaves the duct I 6 through the open damper 36 and into outletduct 22. In this illustration the purpose of reducing the gastemperature to 25 F. saturated was the elimination of moisture. It is tobe understood, of course, that other temperatures and conditions may beused with equally good results. Any sensible heat pickup after reducingthe gas 25 F. saturated is a. gain. Therefore; the gas may now travelthrough the heating coil, which has been designated by the referencenumeral 40, and which is interposed in the outlet duct 22. C011 46 isconnected by pipe circuits 42 and 44 to cooling coil 32 to form a heatreclamation cycle. A pump 46 is interposed in the pipe circuits 42 and44 to circulate the heat exchange medium from cooling coil 32 to heatingcoil 46 and back again.

The heating coil 40 restores to the gas, as sensible heat, both thelatent and sensible heat which the cooling coil 32 abstracted. Thus thegas has been dehumidifled to the equivalent of 25 F. saturated, butleaves the apparatus with part of the sensible heat restored, which hadto be removed for dehumidiflcation. Conversely, this heat reclamationcauses the heat exchange medium to be reduced in temperature by thepassage of 25 F. gas over the heating coil 46. The heat exchange medium,thus reduced in temperature, is returned to the cooling coil 32 at alower temperature than at which it left the same coil, thus causing adirect saving in the amount of refrigeration required to reduce the gastemperature to 25 F. The coil 40 might be omitted entirely, and it needonly be used when it is desired to raise the outlet temperature of gasemitting either from the coils 26 or 36. If desired, the coil 32 mayalso be omitted from the apparatus. In this illustration given above,the gas now leaves the apparatus through the outlet duct 22 at a dewpoint temperature of 25 F., but a dry bulb temperature of 60 F.

As in all refrigeration dehumidifying apparatus where it is necessary touse a cooling medium at or below the frost point, ice or frost will formon the coil or other apparatus used for heat transfer purposes. In theillustration given above ice has gradually accumulated on the coil 36until its effectiveness as a transfer medium is about to be impaired.The defrosting of the coil 36 and the simultaneous transfer of thefunction of dehumidifying and cooling from the coil 36 to the coil 26may be accomplished as follows:

The cooling coils 26 and 36 are supplied with a cold heat exchangemedium, for. example, brine from a refrigeration unit 48 through a pipecircuit 56 having a circulating pump 52 therein to circulate the heatexchange medium. The brine circuit is formed by the supply pipe 56 fromthe refrigeration unit 48 to the valves 54 and 56, which selectivelyallow the flow of cooling medium either to the cooling coil 26 or thecooling coil 36. A pump 52 is interposed in the return conduit 66 topull the cooling medium from the coils back to the refrigerating unit46. The valves 54 and 56 are connected to and rendered operative by thevalves 62 and 64, respectively, these latter valves 62 and 64 beingconnected to a pneumatic temperature controller 93 by line 69. Thetemperature controller 93 is connected to a power supply 68, either air(as shown) or electric or other suitable power means, and is responsiveto a thermally sensitive element, generally designated by the referencenumeral 92 to regulate the amount of flow of the brine.

If desired, a precooling unit I06 may be interposed in the inlet airduct I2. This precooling unit I60 may use cold water or any othersuitable cooling medium. This precooling coil I then operates to coolthe warm, unconditioned air or gas entering the apparatus thus removinga portion of the moisture from the air or gas in liq-,

uid. form. The removal of this moisture lengthens the time that it takesfor the cooling coils 26 and 36 to frostup. The cooling coils 26 and 36are thus kept operating for longer periods of time without the necessityof changing the air flow the apparatus operates more efllciently when aportion of the moisture is removed by said precooling, for the emciencyof the cooling coils is impaired by the deposition of frost on thecoils, and the longer this can be prevented the more efficient theapparatus. As an alternative method of construction, if desired, thecooling coil which has been designated by the reference numeral 32 maybe moved from its position between the cooling coils 26 and 36 as isshown most clearly in l, and positioned in the air or gas inlet I2 tooccupy the position of the precooling coil I60 as shown in Fig. 1. Ifthe coil 32 is positioned in the air or gas inlet I2, then the warmentering air or gas may be cooled and a portion of the moisture may beremoved from said air or gas as liquid. Removal of any moisture from theincoming air or gas lengthens the time that it takes for the coolingcoils 26 and 36 to frost up. It has also been found that positioning thecoil 32 in the air inlet I2 rather than between the coils 26 and 36, asshown in Fig. 1, results in a higher exit temperature of the air fromthe outlet 22 since the reheating coil 40, which is connected to thecoil 32 by suitable conduits which contain heat exchange medium,operates at a higher temperature since the heat exchange medium in theseconduits is not cooled as much as when the cooling coil 32 is positionedbetween the cooling coils 26 and 36. When the coil 32 is positioned inthe air inlet I2, or when a precooling coil I00 is used in the air inletI2, the incoming air or gas is cooled so that it takes somewhat longerto defrost the coils 26 or 36 when they have become frosted up than whenthe warm entering air or gas is allovged to flow directly over thefrosted coils 26 or 3 In the sequence of operations described above thecold heat exchange medium is only supplied to coil 36, the flow of thismedium being shut off to coil 26 by valve 54. As accumulations of iceand frost on the coil 36 develop, it is necessary to shift to coolingcoil 26 if the efficiency of the apparatus is to be maintained. Thisshift is accomplished as is shown most clearly in Fig. 2. The arrowsindicate the direction of gas flow. In Fig. 2 the top drawing labeledCycle A shows the flow of gas as described in the illustration justgiven. In this cycle the gas enters the inlet duct I4 and flows into theduct I6, since the damper 24 is in a closed position and shuts off theduct I8. The gas then flows through coil 26, defrosting said coil, andthenenters the duct 20 through the open damper 28 and passes through thecoil 32 and out into duct I8 through open damper 34. Here the gas flowsthrough cooling coil 36, which is operating, and then out through theoutlet duct 22 and through the reheating coil 46. The second drawing ofFig. 2, which is labeled Cycle A to B, shows a transition period betweenthe shift from operating cooling coil 36 to operating cooling coil 26.As the cooling coil 36 begins to-lose efiiciency due to accumulations ofice and frost, the damper 24 is shifted by means of driving motor 60actuated by valve I6, so that duct I6 is shut off. Simultaneouslydriving motor I4 actuated by valve I8 closes the dampers 34 and 28, towhich it is connected by means of a suitable linkage designatedgenerally by the reference numeral 84, and valve 54 opens to admitrefrigerant flow to coil 26 to precool this coil. The gas enteringthrough inlet duct I2 now passes into duct I6, and then passes directlythrough cooling coil 36 and out the outlet duct 22 and through retodefrost the coil. It has also been found that heating coil 40. Duringthis cycle, which continues only for a relatively short period of time,coil 36 is operating, and coil 26 has refrigerant flowing therethroughand is therefore being precooled.

The third drawing of Fig. 2, labeled "Cycle B shows subsequentoperation; Valve 80 actuates driving motor 82, which opens dampers l2and tsaid dampers being connected to the driving motor 32 by means of asuitable linkage 85. At the same time the valve 83 actuates drivingmotor d to shift the damper 3d so as to close duct id. Gas entering theduct i2 now passes into duct iii and over coil it, defrosting said coil.The gas then passes through the open damper t0 and over coil 32, thenthrough open damper l2, over cooling coil 2t, then passes out the outletduct 22, and through reheat coil t. In this cycle, coil lit is beingdefrosted, and coil 2B is cooling the as.

The last drawing of Figure 2, which has been labeled Cycle B to A showsthe transition as the cooling coil 2% loses efldciency due toaccumulations of ice and frost. Driving motor 60 is actuated by valveto, and shifts damper 2t to close on duct it, and at the same time valve80 actuates driving motor 02 to close dampers i2 and t0 and valve toopens to admit refrigerant to coil 3% to precool this coil. The gasentering through inlet duct it now passes through duct it and directlythrough coil 2t, and then out the outlet cycle coil it is operating, andcoil as has refrigerant flowing therethrough and is therefore beingprecooled. Like cycle A to B this cycle. is of relatively shortduration, after which the operations are repeated-the drawing labeled.Cycle A showing the positions of the dampers and the flow of gas justdescribed. These cycles, above described, may be repeated as often asdesired with either manual control or an automatic device, such as acycle timer, or other suitable automatic apparatus, to make entirelyautomatic the functioning of the apparatus. While we have shown ourapparatus with numerous motors and controls, it is to be understood thatthe apparatus may be greatly simplified, for example, a single motorwith suitable linkage and earns may be used to operate the dampers 2t,3t, 30, 28, I2, and 33.

It is apparent from the above description that the method of operationused in the present invention is a continuously operating system for thedelivery of gas or air at dew points as low as the frost point, orlower, without the necessity of shutting down the apparatus fordefrosting or deicing. It will also be readily apparent that the presentinvention does away with the necessity of duplicating apparatus.

In order to demonstrate further advantages of the apparatus of thepresent invention described herein, reference may be made to a technicalproblem of cooling 10,000 C. F. M. of free air or gas, which on enteringthe apparatus at 70 F. saturated, leaves at a final condition of 60 F.dry bulb and F. dew point. The conditioning of the air or gas, as setforth in the above example, might be obtained by the use of a singlecooling coil such as the cooling coil 26 or at, and then reheated, but arefrigeration requirement of 90 tons would be necessary. However, by theuse of the new and improved apparatus of the present invention,utilizing the here in described method of dehumidifying and reheating,it is possible to reduce the refrigeration all) i 6 load from 90 tons to56 tons, and at the same time deliver this gas or air at the same dewpoint.

A thermally sensitive element 92 is responsive to the temperature of theoutgoing air in the outlet 22 and is connected to pneumatic temperaturecontroller 93 to control the operation of valves 5t and 56 and toregulate the amount of refrigerant which is supplied to these coolingcoils. In this manner the temperature and/or the humidity of theoutgoing air may be accurately controlled.

The thermally sensitive element 92 and pneumatic temperature controller90 by proper controls and apparatus, may also be used to selectivelydirect the flow of cooling medium either to the cooling coil 26 or thecooling coil 36 and may also be used to control the operation of thedriving motors 60, it, 82 and 90, which in turn control the operation ofthe dampers 2t, 3t and 20, i2 and 30, and 38, respectively so as todirect the flow of air initially either through the duct It or the ductIt as previously described.

The cycle would be changed in the following manner. Assume that thesystem is operating on cycle A as shown in Fig. 1. As coil 36 becomesfrosted the temperature in duct 22 tends to rise, but element 92 andtemperature controller 93 cause the valve 56 to increase the flow ofbrine to maintain the control temperature. However, a point is reachedwhen the maximum possible flow of brine is going through the coil, andbecause of the frost on the coil the temperature in duct 22 continues torise. Element 02 and temperature controller 93 respond to this abnormaltemperature rise and the temperature controller 93 sends out a pressureabove normal control pressure. This abnormal pressure, byproper controlssuch as a program device, is then used to actuate the valves 62, 6t, l0,i8, 80, and 88 in the proper sequence to produce changes in the cycle asdescribed above. Such controls are well known in the art and it is notconsidered necessary to show them in detail.

If it is desiredto control the operation of the said valves, motors anddampers responsive to an interval of time, then a device (not shown)designed to operate a valve upon the lapse of a predetermined intervalof time may be used either in conjunction with or substituted for thepneumatic temperature controller or, an instrument (not shown)responsive to the accumulation of frost 'on the cooling coils 2t and 36may be either used in conjunction with or substituted for the thermostat92.

Although the term air has been used in the specification and the claims,it is to be understood that we are using the word air in its genericsense to mean atmospheric air or any other gas, for the apparatus ofthis invention is suitable for heating any type of air or gas and we donot wish to limit our applications to atmospheric air alone. It is alsoto be understood that the illustrations and examples given have been byway of illustration and not limitation since various changes andmodifications may be made.

ducts first as desired, and means to supply refrigerant to whichever ofsaid coils is last in the path of said air, and to cut oil the supply ofrefrigerant to the coil first in the path of said air, both of said lasttwo means being responsive to conditions indicating that one of thecoils in the ducts has becomefrosted.

2. In an air conditioning apparatus comprising a casing with air inletand outlet and two ducts, means to move air through said casing andthrough a first coil positioned in one of said ducts and then through asecond coil positioned in the other of said ducts, means to selectivelysend the air through one or the other of said ducts first as desired,and means to supply refrigerant to whichever of said coils is last inthe path of said air "and to cut of! the supply of refrigerant to thecoil first in the path of the air.

3. In an air conditioning apparatus comprising a casing with air inletand outlet and two ducts, means to move air through said casing andthrough a first coil positioned in one of said ducts, and then through asecond coil positioned in the duct space between the said two ducts andthen through a third coil positioned in the other of said ducts, meansto selectively send the air through one or the other of said ducts firstas desired, and means to supply refrigerant to whichever of said coilsis last in the path of said air and to cut off the supply of refrigerantto the coil first in the path of the air.

4. In an air conditioning apparatus comprising a casing with air inletand outlet and two ducts, means to move air through said casing andthrough a first coil positioned in one of said ducts, then through asecond coil positioned in the duct space between the said two ducts andthen through a third coil positioned in the other of said ducts, meansto selectively send air through one or the other of said ducts first asdesired, and means to alternately supply refrigerants to one and thenthe other of the said first and third cooling coils in said ducts, and areheating coil positioned in the path of air emitting from said outletand operatively connected by conduits containing heat exchange mediumwith the aforesaid second cooling coil.

5. In an air conditioning apparatus comprising a casing with an airinlet and outlet and two ducts, means to move air through said casingand through a first cooling coil positioned in one of said ducts andthen throu'gh a second cooling coil positioned in the other of saidducts, means to selectively send air through one or the other of saidducts first as desired, means to alternately supply refrigerant to firstone and then the other of said cooling coils, both of said last twomeans being responsive to conditions indicating that one of said coilshas become frosted.

6. An apparatus of the type described comprising a casing with air inletand outlet and two ducts, a cooling coil positioned in one of saidducts, a second cooling coil positioned in the other of said ducts,means to move air through said casing and alternately through either ofsaid ducts and cooling coils first as desired, and means to alternatelysupply refrigerant to first one and then the other of said coolingcoils, both of said last two means being responsive to conditionsindicating that one of said cooling coils has become frosted.

7. An apparatus of the type described comprising a casing with air inletand outlet and two ducts, a cooling coll positioned in one of saidducts. a second cooling coil positioned in the other 8 of said ducts,means to move air through said casing and alternately through either ofsaid ducts and cooling coils first as desired, and means to alternatelysupply refrigerant to first one and then the other of said coolingcoils, a third cooling coil positioned in the space between said ductsand operatively connected by ducts containing heat exchange medium witha reheating coil positioned in the path of air emitting from saidoutlet.

8. An apparatus of the type described comprising a casing with air inletand outlet and two ducts, a cooling coil positioned in said inlet topre-cool air fiowing through the apparatus, means to move air throughsaid casing and through a second cooling coil positioned in one of saidducts and then through a third cooling coil positioned in the other ofsaid ducts, means to selectively send the air through one or the otherof said ducts first as desired, and means to supply refrigerant towhichever cooling coil is last in the path of said air and to cut oil.the supply of refrigerant to the cooling coil in the other duct,

9. An apparatus of the type described comprising a casing with air inletand outlet and two ducts, a cooling coil positioned in said inlet topre-cool air flowing through the apparatus, means to move air throughsaid casing and through a second cooling coil positioned in one of saidducts and then through a third cooling coil positioned in the other ofsaid ducts, means to selectively send the air through one or the otherof said ducts first as desired, and means to supply refrigerant toWhichever cooling coil is last in the path of said'air, and to cut offthe supply of refrigerant to the cooling coil in the other duct, both ofsaid last two means being responsive to conditions indicating that oneof the cooling coils in the ducts has become frosted.

10. In an air conditioning apparatus comprising an air inlet and outletand two ducts, a cooling coil positioned in said air inlet, and areheating coil positioned in said air outlet and connected to saidcooling coil in said inlet by conduits containin heat exchange medium,means to move air through said air inlet and cooling coil and thensuccessively through a second cooling coil positioned in one of saidducts and then through a third cooling coil positioned in the other ofsaid ducts and then through said reheating coil and out the said airoutlet, and means to selectively send the air through one or the otherof said ducts first as desired, and means to supply refrigerant towhichever cooling coil is last in the path of said air and to cut offthe supply of refrigerant to the cooling coil in the other duct.

11. In an air conditioning apparatus comprising an air inlet and outletand two ducts, a cooling coil positioned in said air inlet and areheating coil positioned in said air outlet and connected to saidcooling coil in said inlet by conduits containing heat exchange medium,means to move air through said air inlet and cooling coil and thensuccessively through a second cooling coil positioned in one of saidducts and then through a third cooling coil positioned in the other ofsaid ducts and then through said reheating coil and out the said airoutlet, and means to selectively send the air through one or the otherof said ducts first as desired, and means to supply refrigerant towhichever cooling coil is last in the path of said air and to cut of!the supply of refrigerant to the coolin coil in the other duct, both ofsaid last two :4 be responsive to conditions indicating that one of thecooling coils in the ducts has become frosted.

it. A fluid conditioning apparatus comprising a w having an inlet duct,an outlet duct, and two branch ducts connecting said inlet duct and saidoutlet duct, a heat exchanger in each of said branch ducts, means formoving fluid from said inlet duct to said outlet duct, movable means insaid casing for directing said fluid from said inlet duct to said outletduct first through one of said heat exchangers and then through theother of said heat exchangers, means for moving said movable means todirect said fluid from said inlet duct first through said other of saidheat exchangers and then through said one of said heat exchangers, andmeans to supply refrigerant to whichever of said heat exchangers is lastin the path of said fluid.

it. A fluid conditioning apparatus comprising inlet duct and an outletduct, 'a first duct ooecting said inlet duct and said outlet duct,

9. second duct connecting said inlet duct and said outlet duct, a firstheat exchanger in said recting said fluid from said inlet duct to said1' outlet duct first through said first coil and then through saidsecond coil, and means for moving said valve means to direct said fluidfrom said inlet duct to said outlet duct first through-said secondcoiland then through said first coll.

CLARENCE L. RINGQUIST. ROBERT G. MINER.

REFERENCES CITED The following references are of record in the file ofthis patent:

mm STATES PATENTS Number N i r 2,185,047 Weinstein Dec. 26, 1939 12,200,118 Miller May 7, 1940 2,445,705 Weinstein July 20, 1948

